When industrial robots for arc welding or the like are used for a welding process in which high-frequency noise is produced, for example, TIG welding, the high-frequency noise caused by an arc enters signal lines and causes problems such as malfunctions or the generation of an alarm. To avoid such problems, covers for components such as servomotors are made of a metallic plate, e.g., iron plate or the like. The iron plate cover is fixed by screws, although a coating thereon is removed from the portion at which the screws are used, to provide a shielding effect for signal lines to be arranged therein. Obviously, all of the signal lines may use shielded wires to avoid the influence of noise, but it is difficult to use shielded wires for all of the signal lines, due to structural limitations peculiar to industrial robots.
Plastic covers are now widely used as the covers for industrial robots, to meet demands for a reduction of manufacturing costs and for a lighter weight, but this type of cover does not provide the shielding effect obtained from the iron plate cover.